Chemtrac Auto Clean UV254, Руководство пользователя, Страница: 14 / 41

Chemtrac UV254 Monitor
– UVM5000 v 2.1
Chemtrac, Inc. 13
5.6
Turbidity and Filtration
Depending on the application, the role of turbidity can be
treated either as a part of the measurement, or as an
interference in the measurement.
For example, a UV disinfection application will generally
require a transmittance measurement that includes the
effects of both dissolved organics and light blocking
particulate, whereas an organics monitoring application will
often require a measurement of the organics isolated from
the light blocking effects of particulate.
Because of this,
Chemtrac’s monitors can include an
optional 550 nm turbidity compensation measurement.
Since 550 nm light is not significantly sensitive to organic
material but is sensitive to light blocking particulate, the
550-nm turbidity compensation measurement can provide
an isolated measurement of turbidity that allows this
turbidity component to be extracted from the 254-nm
measurement. This results in a measurement of organics
material independent of turbidity and particulate in the
water. The same results can also be achieved by removing
light blocking particulate from the sample stream through
filtration.
5.6.1
Turbidity Compensation (Optional)
Optional turbidity compensation can be added to any
UV254 analyzer. Turbidity compensation allows for
sampling without filtration in water with turbidity levels
below ~60 NTU. Above 60 NTU, a 50-200-micron filter
should be installed prior to sampling. If 50-micron is not
sufficient to obtain 60 NTU on the filter effluent, a 20-micron
filter should then be added. Refer to menu item Turbidity
Comp. in Section 9, Menu Structure, to enable the turbidity
compensation feature.
5.6.2
Filtering
All UV254 analyzers without turbidity compensation can
obtain an accurate reading of dissolved organic matter at
a turbidity level below ~10 NTU. If the sample water has
turbidity levels that fluctuate above 10 NTU, a 50-micron
filter should be installed prior to sampling. Should 50-
micron not be sufficient to obtain 10 NTU on the filter
effluent, a 20-micron filter should then be added.